Subtraction fact · doubles
18 − 9 = 9
Eighteen minus nine is nine. 18 is double 9, so taking away 9 leaves the other half.
See 18 − 9
18 counters, 9 crossed out, 9 left.
It's half of a double
- Remember the double: 9 + 9 = 18.
- Take one of those 9s away.
- The other 9 is left, so 18 − 9 = 9.
Its fact family has two facts
9, 9 and 18 go together, so learning one of these helps with all of them. See the family.
Practice 18 − 9 in a game
A fact sticks when a child has to pull it from memory again and again. In this game 18 − 9 keeps coming back between the other facts in its family.
Every round leans on 18 − 9
Free to play · no signup · works on phones, tablets and computers
Quick quiz
18 − 9 FAQ
What is 18 − 9?
18 − 9 = 9. In words: eighteen minus nine is nine.
How can I check 18 − 9 = 9?
Add back: 9 + 9 = 18. If the addition gives the number you started with, the subtraction is right.
What grade learns 18 − 9?
This is a first and second grade fact. Common Core has children subtract within 20 in first grade (1.OA.C.6) and do it fluently with mental strategies in second grade (2.OA.B.2).
Is Sumtown really free?
Yes. The whole game plays free in your browser, with no signup, no ads and no time limit. All fourteen mini games are in it. An iPhone app is on its way, and you can read what it will add.
An app is on its way
We're building a Sumtown app for iPhone with the parts that need a real app: offline play for car rides, a town map that remembers how far your child got, and a parent report on every fact. Until then, the whole game is free right here.
Coming soon on theApp Store